Anti-inflammatory and mutagenic evaluation of medicinal plants used by Venda people against venereal and related diseases

Ethnopharmacology relevance

Inflammation is a major risk factor for various human diseases including venereal diseases, often resulting in treatment complications. Plants have been traditionally used for treatment of many different diseases and have been successfully proven to be an alternative source in treatment of infectious diseases.

Aim of the study

This study was aimed at evaluating the anti-inflammatory activities and the mutagenic properties of 12 medicinal plants used by the Venda people against venereal and related diseases.

Materials and methods

The plants were evaluated for their anti-inflammatory activity against the cyclooxygenase (COX-1 and -2) enzymes and genotoxicity using the Ames test, with and without S9 (metabolic activation) against Salmonella typhimurium tester strain TA98.

Results

DCM and PE extracts of Adansonia digitata bark, Bolusanthus speciosus bark, Pterocarpus angolensis bark and Pappea capensis leaves and EtOH and water extracts of Bolusanthus speciosus stem and Ekebergia capensis bark showed the best anti-inflammatory activity in both COX-1 and -2 assays at 250 μg/ml. These were further evaluated at three other concentrations (31.25, 62.5, and 125 μg/ml) to determine IC₅₀ values. Water extracts of Ekebergia capensis bark showed the best IC₅₀ value towards COX-1. The Ames test revealed that all plant extracts were non-mutagenic towards Salmonella typhimurium strain TA98 except for Elephantorrhiza burkei and Ekebergia capensis that showed weak mutagenicity.

Conclusion

The active plants may offer a new source of chemicals for the effective treatment of anti-inflammatory conditions related to venereal diseases.     

Antibacterial activities of plants from Central Africa used traditionally by the Bakola pygmies for treating respiratory and tuberculosis-related symptoms

Ethnopharmacological relevance

The antibacterial activities of 18 plants from 10 different families were investigated for their antimicrobial efficacy, based on the traditional uses of these species by Bakola pygmies living in Central Africa, especially along the Ngoyang area in Cameroon for the treatment of respiratory and tuberculosis-related symptoms. The aim of the study is to test the antimicrobial efficacy of these plants against some pathogens associated with respiratory disease and to determine if there is any validation for the traditional use against Mycobacterium species.

Materials and methods

Medium polar extracts were prepared in MeOH/DCM (1:1, v/v) from the plant parts of each species used traditionally and were assayed against pathogens associated with respiratory tract ailments [Staphylococcus aureus (ATCC 25923), Klebsiella pneumoniae (ATCC 13883) and Morexella cattarhalis (ATCC 14468)] using the minimum inhibitory concentration (MIC) method. Two additional faster growing Mycobacterium strains [Mycobacterium smegmatis (ATCC 23246) and Mycobacterium aurum (NCTC 10437)] were included in the assay as predictive test organisms for the more pathogenic strain Mycobacterium tuberculosis.

Results

Some plant species, such as Alchornea floribunda, Musanga cecropioides (both leaves and stem bark), Tetracera potatoria and Xylopia aethiopica (stem bark), were effective in inhibiting Morexella cattarhalis, having MIC values between 65 and 250 μg/mL. Some noteworthy antimycobacterial inhibition (MIC≤200 μg/mL and as low as MIC 6.5 µg/mL) for 54% of the extracts were observed.

Conclusion

While moderate activity was shown for pathogens causing respiratory tract infections, these plant species seems to be selectively targeting Mycobacteria spp. suggesting that the traditional use for treating tuberculosis related symptoms may be indeed be accurate.     

Ethnopharmacological study of plants from Pondoland used against diarrhoea

Ethnopharmacological relevance

Waterborne diseases such as diarrhoea are common world wide, including in Bizana, South Africa where the majority of rural dwellers depend largely on water from unprotected sources. The people from Bizana use medicinal plants as their first line of health care to cure and prevent diarrhoea.

Aim of the study

To record and document plants used for the treatment of diarrhoea in Bizana, to evaluate antibacterial and anti-inflammatory activities of selected plant extracts as well as to perform genotoxicity testing of evaluated plants.

Materials and methods

An ethnobotanical approach was used to select plants used for treating diarrhoea in Bizana for pharmacological assays using questionnaires. Nine plants were selected for bioassays based on their frequency index and the fact that they have never been evaluated against diarrhoea causing-microorganisms. The petroleum ether (PE), dichloromethane (DCM), 70% ethanol (EtOH), and water extracts were evaluated for antibacterial (Gram-positive Staphylococcus aureus, Gram-negative Escherichia coli and Shigella flexneri) activity using the microdilution technique, their ability to inhibit COX-1 and COX-2 enzymes. Genotoxicity was evaluated using the Salmonella microsome assay.

Results

This study revealed that 34 plant species belonging to 27 families are used for the treatment of diarrhoea in Bizana. The extracts showed good inhibitory activity with MIC values ranging from 0.39 to 12.5 mg/ml. The best activity was exhibited by DCM extracts of Rapanea melanophloeos, and EtOH extracts of Ficus craterostoma and Maesa lanceolata with MIC values of 0.098 mg/ml. The inhibitory activity against COX-1 enzyme was higher than COX-2, with 19 plant extracts for the former and 7 for the latter. All the tested plant extracts were not mutagenic at all concentrations tested against all tester strains of bacteria.

Conclusion

In view of the fact that the plants were selected based on their ethnobotanical usage for treating diarrhoea, the activities reported here goes a long way in validating the plants for traditional use.     

An antimicrobial evaluation of plants used for the treatment of respiratory infections in rural Maputaland,KwaZulu-Natal,South Africa

Ethnopharmacological relevance

Abundant availability of medicinal plants in the study area offers low cost health care, but scientific validation is needed in order to lend credibility to the traditional use against respiratory infections.

Aim of the study

This study focussed on determining the antimicrobial efficacies of 30 plant species (independently and in various combinations) used for respiratory related infections in rural Maputaland.

Materials and methods

In vitro minimum inhibitory concentration (MIC) assays were undertaken on dichloromethane-methanol (CH₂Cl₂: MeOH) and aqueous extracts, as well as the hydro-distilled essential oils (for aromatic plants). Selected plant parts were assessed for antimicrobial activity against a range of respiratory pathogens i.e. Cryptococcus neoformans (ATCC 14116), Klebsiella pneumoniae (ATCC 13883), Moraxella catarrhalis (ATCC 23246), Mycobacterium smegmatis (ATCC 14468) and Staphylococcus aureus (ATCC 6538). The sum of the fractional inhibitory concentrations (∑FIC) was determined for plants traditionally used in combination. Isobolograms represent MIC values for a selection of interactions where two plants were combined in various ratios.

Results

The most antimicrobially active aqueous extracts were that of Ozoroa obovata and Sclerocarya birrea (0.10 mg/ml) while organic extracts from Parinari capensis subsp. incohata and Tetradenia riparia demonstrated the most noteworthy (0.03 mg/ml) activity. Although both Lippia javanica and Eucalyptus grandis were by far the most popular plants traditionally used for respiratory infections, the antimicrobial activity was mostly only moderate. Furthermore, the traditional use in a 1:1 combination did not display strong antimicrobial interactions, but isobolograms demonstrate (against some test organisms) that when combined in various ratios, predominant additive interactions are evident where E. grandis was present in larger proportions. The combination of E. grandis with O. obovata demonstrated synergism against both C. neoformans and K. pneumoniae, with ∑FIC values of 0.34 and 0.28 respectively. Various ratios of these two plants also demonstrated a predominantly synergistic profile.

Conclusion

Although this in vitro study supports the traditional use of some plants independently and in combination for the treatment of respiratory ailments in rural Maputaland, results demonstrate that the traditional selection of plants in higher frequency do not necessarily correlate with higher antimicrobial efficacy.     

Medicinal plants used for the treatment of diarrhoea in northern Maputaland,KwaZulu-Natal Province,South Africa

Aim of the study

To document the ethnobotanical knowledge on antidiarrhoeal plant use by lay people in a rural community in northern Maputaland.

Materials and methods

Interviews were conducted amongst homestead inhabitants, using structured questionnaires. The focus was on the medicinal plants which are growing in and around the immediate vicinity of the homesteads.

Results

Twenty-three plant species are used in the study area to treat diarrhoea. Four plants (Acacia burkei, Brachylaena transvaalensis, Cissampelos hirta and Sarcostemma viminale) are recorded for the first time globally as an antidiarrhoel. The three antidiarrhoeal plants most frequently used in the study area are Psidium guajava, Catharanthus roseus and Melia azedarach (all three are exotic to South Africa), followed by Sclerocarya birrea and Strychnos madagascariensis which are indigenous. Seven of the 23 plant species are used in five different plant combinations for increased antidiarrhoeal efficacy.

Conclusion

The wide variety of plants that are used to treat diarrhoea in this area supports the traditional value that medicinal plants have in the primary health care system of the rural people in northern Maputaland, KwaZulu-Natal.     

The antimicrobial,antioxidative, anti-inflammatory activity and cytotoxicity of different fractions of four South African Bauhinia species used traditionally to treat diarrhoea

Ethnopharmacological importance

Many Bauhinia species, including those indigenous to South Africa, are used in traditional medicine across the world for treating ailments such as gastrointestinal tract (GIT) disorders, diabetes, infectious diseases and inflammation.

Aims

Several relevant aspects of different fractions of leaf extracts of Bauhinia bowkeri (BAB), Bauhinia galpinii (BAG), Bauhinia petersiana (BAP), and Bauhinia variegata (BAV) used in South African traditional medicine to alleviate diarrhoea related symptoms were evaluated.

Materials and Methods

The antioxidative activities of the extracts were determined using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH), 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS⁺) radical scavenging and ferric reducing antioxidant power (FRAP) methods. In vitro antimicrobial activities of the extracts were determined against bacterial strains (Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecalis) and clinical isolates of the opportunistic fungal strains (Aspergillus fumigatus, Candida albicans, and Cryptococcus neoformans) using a serial dilution microplate method. The polyphenolic contents were quantified using standard methods, and anti-inflammatory activities of the crude extracts were determined using the cyclooxygenase and soybean 15-lipoxygenase enzyme inhibitory assays. The safety of the extracts was evaluated by determining the cytotoxicity against Vero cell lines.

Results

The acidified 70% acetone crude extract and their fractions had good antiradical potency against the DPPH and ABTS radicals. The methanol soluble portions of the butanol fractions were more potent (EC₅₀ ranges from 0.64±0.05 to 1.51±0.07 and 0.88±0.18 to 1.49±0.09 μg/ml against DPPH and ABTS radical respectively) compared to the standard, trolox and ascorbic acid (EC₅₀ ranges from 1.47±0.24 to 1.70±0.27 μg/ml) for both DPPH and ABTS. The crude extracts contained variable quantities of phenolic content. The crude extracts and their fractions had weak to good antimicrobial activities, inhibiting the growth of the organisms at concentrations ranging from 39 to 2500 μg/ml. The BAG crude extract and its fractions were the most active against the fungi (MICs ranging from 39 to 625 μg/ml) while the BAB extract and its fractions were the least active with the MICs ranging between 39 and 2500 μg/ml. Aspergillus fumigatus was the least susceptible fungus while Cryptococcus neoformans was the most susceptible.The phenolic-rich crude extracts of BAB, BAG, and BAP had moderate to good dose-dependent cyclooxygenase-1 enzyme inhibitory activity with inhibitions between 22.8% and 71.4%. The extracts were however, inactive against cyclooxygenase-2. The extracts had some level of cytotoxicity towards Vero cell lines, reducing cell viability to less than 10% at concentrations more than 50 μg/ml.

Conclusion

The biological activities observed in Bauhinia species provide a scientific basis for the use of the plants in traditional medicines to treat diseases with multi-factorial pathogenesis such as diarrhoea, with each aspect of activity contributing to the ultimate therapeutic benefit of the plants. However, the use of the phenolic-rich extracts of these plants to treat diarrhoea or any other ailments in traditional medicine needs to be monitored closely because of potential toxic effects and selective inhibition of COX-1 with the associated GIT injury.     

Plant composition, pharmacological properties and mutagenic evaluation of a commercial Zulu herbal mixture: Imbiza ephuzwato

Ethnopharmacology relevance

Imbiza ephuzwato is a traditional herbal tonic made from a mixture of extracts of roots, bulbs, rhizomes and leaves of 21 medicinal plants and is used in traditional medicine as a multipurpose remedy.

Aim of the study

To compile and investigate the bioactivity and mutagenic effects of extracts of the 21 plant species used in the preparation of Imbiza ephuzwato herbal tonic.

Materials and methods

The 21 plant species used to make Imbiza ephuzwato herbal mixture were each investigated for their pharmacological properties. Petroleum ether (PE), dichloromethane (DCM), 80% ethanol (EtOH) and water extracts of the 21 plants were evaluated against two gram-positive, two gram-negative bacteria and a fungus Candida albicans. The extracts were also evaluated for their inhibitory effects against cyclooxygenase (COX-1 and -2) and acetylcholinesterase AChE enzymes. Mutagenic effects of the water extracts were evaluated using the Ames test.

Results

Gunnera perpensa and Rubia cordifolia were the only plant species used to manufacture Imbiza ephuzwato that had water extracts which showed good antibacterial activity. The extracts of G. perpensa (EtOH), Hypericum aethiopicum (DCM) and Urginea physodes (EtOH) showed the best antifungal activity. The water extracts of H. aethiopicum, G. perpensa, Drimia robusta, Vitellariopsis marginata, Scadoxus puniceus and Momordica balsamina showed percentage inhibition of COX-1 that was over 70%. For COX-2 enzyme, the water extracts of G. perpensa, Cyrtanthus obliquus, M. balsamina and Tetradenia riparia exhibited inhibitory activity above 70%. Water extracts of G. perpensa, C. obliquus, V. marginata, Asclepias fruticosa and Watsonia densiflora showed good AChE inhibitory activity (>80%). The Ames test results revealed that all the water extracts of the 21 plant species used to make Imbiza ephuzwato were non-mutagenic towards the Salmonella typhimurium TA98 strain for the assay with and without S9 metabolic activation. In contrast, Imbiza ephuzwato showed mutagenic effects after exposure to S9 enzyme mixture.

Conclusion

The observed activities of some plant extracts, if supported by other confirmatory tests, may justify their inclusion in the makeup of Imbiza ephuzwato herbal mixture as well as their use in traditional medicine. Further studies aimed at investigating possible synergistic effects as a result of mixing plant extracts are necessary. The reported mutagenicity in Imbiza ephuzwato could be as a result of interaction of biomolecules in the heterogeneous mixture, yielding compounds that are converted to mutagenic agents by xenobiotic metabolizing enzymes. It is therefore important to carry out further studies aimed at identifying and eliminating the sources of the mutagenic compounds in the heterogeneous mixture.